A New Unified Understanding Of Electron And Ion Normal Modes In A1D Electrostatic Vlasov-Poisson Plasma

Understanding the dynamics of a collisionless plasma is a subject of extensive effort, for both
space plasma environments as well as for laboratory plasma systems. In these studies, one usually deals with the various time scales, from electron to ion response times. The novel branches of electrostatic waves [Langmuir (LAN), Electron Acoustic (EAW), Ion Acoustic (IA), Ion Bulk (IBk)] have been studied either in the background of immobile ions with kinetic electrons resulting in a“thumb curve” ( LAN, EAW )  or in the frame of Boltzmann electrons with kinetic ions resulting in a “teardrop” curve ( IA, IBk) . Thus, until the advent of this work, the electron scale physics and ion scale physics have been separately studied , whereas the actual physical picture would emerge only when both ion and electron scale dynamics are included self consistently and simultaneously in a framework.

In the present work, using a Vlasov-Poisson solver,  considering both kinetic electrons and kinetic ions on the same physics footing, we demonstrate that the hitherto separate
normal mode branches of electrons and ions are in fact “continuously” connected and can be excited simultaneously for a range of electron to ion temperature ratios and mass ratios, the details of which will be presented.